A substrate processing apparatus that executes a specific type of processing such as etching or film formation on a substrate such as a glass substrate (e.g., a liquid crystal substrate) or a semiconductor wafer (hereafter may be simply referred to as a “wafer”) includes a processing unit achieved by connecting a loadlock chamber two a processing chamber where a wafer, for instance, undergoes the specific type of processing and a transfer chamber through which a wafer is transferred (carried) into/out of the processing unit via a transfer mechanism such as a transfer arm.
In the transfer chamber, an unprocessed wafer stored in a cassette container is taken out and transferred over to the processing unit via the transfer mechanism. The unprocessed wafer is then carried into the processing chamber via the loadlock chamber and undergoes wafer processing in the processing chamber. Once the processing in the processing chamber ends, the processed wafer is carried back into the loadlock chamber from the processing chamber. The processed wafer having been returned to the loadlock chamber is transferred into the transfer chamber via the transfer mechanism which then takes it back into the cassette container.
In order to prevent particles (e.g., dust, dirt, deposits and reaction products) from settling on the wafer and thus ensure that the yield is kept at a desired level in the substrate processing apparatus, an air intake fan for taking in external air through an air intake port and a discharge port are respectively disposed on the upper side and on the lower side of a transfer chamber through which a wafer is transferred through external air. As external air is taken in through the air intake port by driving the air intake fan and is discharged through the discharge port, a specific gas flow (e.g., an air down flow) directed from the upper space toward the lower space inside the transfer chamber is created. Since the substrate processing apparatus is normally installed inside a clean room, the air within the clean room is taken into the transfer chamber and is then returned from the transfer chamber to the clean room.
However, the processed wafer carried back into the transfer chamber for retrieval may bear a processing gas constituent settled thereupon. In such a case, the gas constituent will be discharged from the transfer chamber together with the air inside the transfer chamber into, for instance, a clean room, giving rise to the risk of clean room contamination, depending upon the type of gas constituent contained in the exhaust gas. For instance, if a corrosive gas such as a gas containing Cl or Br is used as the processing gas, air containing corrosive gas constituents, e.g., Cl2, Br2, HCl or HBr) will be discharged from the transfer chamber into the clean room and the equipment installed in the clean room may become corroded by the gas constituents.
As a solution, the discharge port of the transfer chamber may be connected to the plant discharge system (e.g., a decontaminating system, i.e., a gas scrubber) so as to direct all the discharge gas from the transfer chamber to the plant discharge system. However, this solution is bound to greatly increase the onus on the plant discharge system.
It is to be noted that a filter is installed on the air intake side of the substrate processing chamber or a clean room so as to disallow entry of particles and the like into the substrate processing apparatus or the clean room in the known art. For instance, patent reference literature 1 and non-patent reference literature 1 both teach a structure that includes a filter disposed on the air intake side (the upper side) of the entire clean room where a substrate processing apparatus and the like are installed or on the air intake side of a partitioned area within the clean room. Patent reference literature 2 discloses a structure having a filter installed on the air intake side (lateral side) of a vertically oriented heat treatment apparatus.
However, while filters are installed on the air intake side of the substrate processing apparatus and the clean room so as to disallow entry of particles and the like into the substrate processing apparatus and the clean room in the related art, no significant measures are taken on the discharge side. This means that the problems attributable to the gas discharge from the transfer chamber described above cannot be solved simply by adopting the filter in the related art installed on the air intake side of the transfer chamber of the substrate processing apparatus.
[Patent Reference Literature 1]
Japanese Laid Open Patent Publication No. 2001-015578
[Patent Reference Literature 2]
Japanese Laid Open Patent Publication No. H06-224144
[Non-Patent Reference Literature 1]
Kanzawa. K, Kitano. J, “A semiconductor device manufacturer's efforts for controlling and evaluating atmospheric pollution” (Advanced Semiconductor Manufacturing Conference and Workshop, 1995. ASMC 95 Proceedings. IEEE/SEMI 1995), 13-15 Nov. 1995, pp. 190-193